Daniel Sanchez-Crespo provides an overview of AI methods used in fast-paced action games. He reviews general techniques, and then does a case-by-case analysis on fighting games, racing simulators, and so on, providing insider information on many popular algorithms.

Key topics

On Action Games

Choreographed AIs

Object Tracking

Chasing

Evasion

Patrolling

Hiding and Taking Cover

Shooting

Putting It All Together

In Closing

"Action may not always bring happiness; but there is no happiness without
action."

--Benjamin Disraeli

Now that we have a global understanding of the building blocks of any AI system,
it is time to delve into the details of how AI is built into video games. Because
this is a lengthy subject, with different techniques used for different gameplay
styles, I have divided the information into three separate chapters. Most game
AI techniques might not be very complex, but there are many twists and interesting
ideas to which we will have to devote some space.

In this chapter, I will provide an overview of AI methods used in fast-paced
action games. We will review general techniques, and then do a case-by-case
analysis on fighting games, racing simulators, and so on, providing insider
information on many popular algorithms.

The next chapter will deal with the subject of tactical AI, which finds its
main use in strategy games. We will learn to build plans, analyze enemy configurations,
and trace maneuvers that would marvel most real-world generals.

We will end our journey through artificial intelligence techniques with a chapter
on scripting, which is one of the most powerful paradigms for coding AIs. By
separating the AI code from the main game engine, scripting provides a robust
and flexible way of creating large AI systems. In fact, most professional AIs
today are built via some sort of scripting engine. So we will analyze the different
scripting techniques in detail.

Let's begin with the basics. We need to create little creatures that chase
us and shoot, so let's get to work.

On Action Games

For this book, I will define action as intelligent activity that involves
changes of behavior at a fast speed. Examples of action are all locomotion
behaviors (a character that runs in Mario), simple aggression or defense
(enemies shooting or ducking in Quake), and so on. Notice how action is
put in a contraposition to tactical reasoning, which is in turn described as the
analysis process used to create a plan that will then guide the actions of an
intelligent character. So, action deals with immediate activity, and tactics
plan that activity.

Action is thus driven by relatively simple tests. We will need to compute
distances to targets, angular separations, and so on. Action is also quite
fast-paced. Action games have higher rhythms than tactic/strategic games.